Planetary nebula
A 84
Planetary nebula
A shell of gas thrown off by a dying Sun-like star, glowing in the ultraviolet light of the hot core at its centre. Within a few tens of thousands of years it will disperse and fade from view. The distance is a statistical estimate, uncertain by 30–50 %.
| Type | Planetary nebula |
|---|---|
| Constellation | Cassiopeia |
| Distance | 1,220 pc (4.0 thousand ly) · estimated |
| Diameter | 2.3 ly |
| Central star | V 18.5 |
| Expansion speed | 16 km/s |
| PN G name | PN G112.9-10.2 |
| Source | Strasbourg–ESO PN Catalogue |
| Right ascension (J2000) | 23h 47m 44.9s |
| Declination (J2000) | +51° 23′ 57″ |
In the sky
Visible from the whole Northern Hemisphere and south to latitude 39° S. North of latitude 39° N it never sets. It stands highest at midnight in September, the best time to observe it.
Through a telescope from Earth
Light's journey
The light you see tonight set out around 1954 BC. At the speed of Voyager 1, the fastest craft leaving the Solar System (16.9 km per second), the trip would take 71 million years.